Carnosine supplementation improves glucose control in adults with pre-diabetes and type 2 diabetes: A randomised controlled trial.

BACKGROUND AND AIMS: Type 2 diabetes (T2DM) is a major cause of morbidity and mortality globally. Carnosine, a naturally occurring dipeptide, has anti-inflammatory, antioxidant, and anti-glycating effects, with preliminary evidence suggesting it may improve important chronic disease risk factors in adults with cardiometabolic conditions. METHODS AND RESULTS: In this randomised controlled trial, 43 adults (30%F) living with prediabetes or T2DM consumed carnosine (2 g) or a matching placebo daily for 14 weeks to evaluate its effect on glucose metabolism assessed via a 2-h 75 g oral glucose tolerance test. Secondary outcomes included body composition analysis by dual energy x-ray absorptiometry (DEXA), calf muscle density by pQCT, and anthropometry. Carnosine supplementation decreased blood glucose at 90 min (-1.31 mmol/L; p = 0.02) and 120 min (-1.60 mmol/L, p = 0.02) and total glucose area under the curve (-3.30 mmol/L; p = 0.04) following an oral glucose tolerance test. There were no additional changes in secondary outcomes. The carnosine group results remained significant before and after adjustment for age, sex, and change in weight (all>0.05), and in further sensitivity analyses accounting for missing data. There were no significant changes in insulin levels. CONCLUSION: This study provides preliminary support for larger trials evaluating carnosine as a potential treatment for prediabetes and the initial stages of T2DM. Likely mechanisms may include changes to hepatic glucose output explaining the observed reduction in blood glucose without changes in insulin secretion following carnosine supplementation.

Carnosine Did Not Affect Vascular and Metabolic Outcomes in Patients with Prediabetes and Type 2 Diabetes: A 14-Week Randomized Controlled Trial.

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality in patients with prediabetes and type 2 diabetes mellitus (T2DM). Carnosine has been suggested as a potential approach to reduce ASCVD risk factors. However, there is a paucity of human data. Hence, we performed a 14-week double-blind randomized placebo-controlled trial to determine whether carnosine compared with placebo improves vascular and metabolic outcomes in individuals with prediabetes and T2DM. In total, 49 patients with prediabetes and T2DM with good glycemic control were randomly assigned either to receive 2 g/day carnosine or matching placebo. We evaluated endothelial dysfunction, arterial stiffness, lipid parameters, blood pressure, heart rate, hepatic and renal outcomes before and after the intervention. Carnosine supplementation had no effect on heart rate, peripheral and central blood pressure, endothelial function (logarithm of reactive hyperemia (LnRHI)), arterial stiffness (carotid femoral pulse wave velocity (CF PWV)), lipid parameters, liver fibroscan indicators, liver transient elastography, liver function tests, and renal outcomes compared to placebo. In conclusion, carnosine supplementation did not improve cardiovascular and cardiometabolic risk factors in adults with prediabetes and T2DM with good glycemic control. Therefore, it is improbable that carnosine supplementation would be a viable approach to mitigating the ASCVD risk in these populations. The trial was registered at clinicaltrials.gov (NCT02917928).

Aldosterone, Renin, and Aldosterone-to-Renin Ratio Variability in Screening for Primary Aldosteronism.

CONTEXT: The plasma aldosterone concentration (PAC), renin, and aldosterone-to-renin ratio (ARR) are used to screen for primary aldosteronism (PA). Substantial intra-individual variability of PAC and ARR using plasma renin activity in the context of usual antihypertensive therapy has been described, but there is no data on ARR variability calculated using direct renin concentration (DRC). OBJECTIVE: To describe the intra-individual variability of PAC, DRC, and ARR in the absence of interfering medications in patients with and without PA. DESIGN: Retrospective cohort study. PATIENTS: Hypertensive patients referred for investigation of PA, with at least 2 ARR measurements while off interfering medications. SETTING: Endocrine hypertension service of a tertiary center, from May 2017 to July 2021. MAIN OUTCOME MEASURES: PAC, DRC, and ARR variability was calculated as coefficient of variation (CV) and percent difference (PD). RESULTS: Analysis of 223 patients (55% female, median age 52 years), including 162 with confirmed PA, demonstrated high variability with a sample CV of 22-25% in the PAC and sample CV of 41% to 42% in the DRC and ARR in both the PA and non-PA groups. The degree of variability was substantially higher than the assays' analytical CV. Sixty-two patients (38%) with PA had at least one ARR below 70 pmol/L:mU/L (2.4 ng/dL:mU/L), a cut-off for first-line screening of PA. CONCLUSIONS: Significant intra-individual variability in PAC, DRC, and hence ARR occurs in a large proportion of patients being investigated for PA. These findings support the need for at least 2 ARR before PA is excluded or further investigated.

Relationship Between Urinary Phosphate and All-Cause and Cardiovascular Mortality in a National Population-Based Longitudinal Cohort Study.

OBJECTIVES: High dietary phosphate intake may lead to adverse outcomes including cardiovascular disease (CVD). Urinary phosphate excretion, a marker of intestinal phosphate absorption, may be a more reliable marker of phosphate homeostasis in steady state than serum phosphate. Studies report good agreement between urine phosphate-to-creatinine ratio (uPiCr) and 24-hour urinary phosphate; however, whether uPiCr is associated with increased risk of CVD or mortality remains uncertain. This study aimed to assess the relationship between uPiCr and all-cause and CVD mortality. DESIGN AND METHODS: This is an observational longitudinal cohort study using data from the population-based national Australian Diabetes, Obesity and Lifestyle study (n = 10,014 participants). Non-linear association between uPiCr and all-cause and CVD mortality was assessed using fractional polynomial transformations. Cox proportional hazards regression models were used to estimate adjusted hazard ratios for all-cause and CVD mortality. RESULTS: Median age [interquartile range] was 50 [41-62] years, and 46% were male. Median uPiCr was 1.38 [1.02-1.79] mmol/mmol. Median follow-up time was 16.9 years with 1,735 deaths. uPiCr was associated with all-cause and CVD mortality in univariate models and when adjusted for age and gender. However, associations were not significant in multivariate models. Sensitivity analyses excluding participants with chronic kidney disease (CKD) revealed a significant J-shaped association between uPiCr and all-cause mortality. Urine phosphate alone showed an association with increased all-cause mortality in a similar J-shape relationship. CONCLUSION: Although no association between uPiCr and all-cause and CVD mortality was observed in multivariate analyses in the whole cohort, a significant relationship between uPiCr and mortality in those without CKD suggests that uPiCr may have predictive validity for future adverse outcomes in people with no CKD.

Type 2 diabetes after a pregnancy with gestational diabetes among first nations women in Australia: The PANDORA study.

AIMS: To determine among First Nations and Europid pregnant women the cumulative incidence and predictors of postpartum type 2 diabetes and prediabetes and describe postpartum cardiovascular disease (CVD) risk profiles. METHODS: PANDORA is a prospective longitudinal cohort of women recruited in pregnancy. Ethnic-specific rates of postpartum type 2 diabetes and prediabetes were reported for women with diabetes in pregnancy (DIP), gestational diabetes (GDM) or normoglycaemia in pregnancy over a short follow-up of 2.5 years (n = 325). Pregnancy characteristics and CVD risk profiles according to glycaemic status, and factors associated with postpartum diabetes/prediabetes were examined in First Nations women. RESULTS: The cumulative incidence of postpartum type 2 diabetes among women with DIP or GDM were higher for First Nations women (48%, 13/27, women with DIP, 13%, 11/82, GDM), compared to Europid women (nil DIP or GDM p < 0.001). Characteristics associated with type 2 diabetes/prediabetes among First Nations women with GDM/DIP included, older age, multiparity, family history of diabetes, higher glucose values, insulin use and body mass index (BMI). CONCLUSIONS: First Nations women experience a high incidence of postpartum type 2 diabetes after GDM/DIP, highlighting the need for culturally responsive policies at an individual and systems level, to prevent diabetes and its complications.

Phagocyte extracellular traps in children with neutrophilic airway inflammation.

Childhood lung infection is often associated with prominent neutrophilic airway inflammation and excess production of proteases such as neutrophil elastase (NE). The mechanisms responsible for this inflammation are not well understood. One potentially relevant pathway is the production of extracellular traps by neutrophils (NETs) and macrophages (METs). The aim of this study was to measure NET and MET expression in children and the effect of deoxyribonculease (DNase) 1 and α1-antitrypsin (AAT) on this process. We studied 76 children (median age of 4.0 years) with cystic fibrosis or chronic cough who underwent investigational bronchoscopy. NETs, METs and neutrophil elastase activity in bronchoalveolar lavage (BAL) samples were measured using confocal microscopy and functional assays. The effects of DNase 1 and AAT on NET/MET expression and neutrophil elastase activity were examined in vitro. Both subject groups had airway neutrophilia with prominent BAL production of NETs with neutrophil elastase co-expression; the mean %±standard error of the mean of neutrophils expressing NETs in the cystic fibrosis group was 23.3±2.8% and in the non-cystic fibrosis group was 28.4±3.9%. NET expression was higher in subjects who had detectable neutrophil elastase activity (p≤0.0074). The percentage of macrophages expressing METs in the cystic fibrosis group was 10.7±1.2% and in the non-cystic fibrosis group was 13.2±1.9%. DNase 1 decreased NET/MET expression (p<0.0001), but increased neutrophil elastase activity (p≤0.0137). The combination of AAT and DNase 1 reduced neutrophil elastase activity (p≤0.0049). We observed prominent extracellular trap formation in symptomatic children with and without cystic fibrosis. This innate inflammatory response was down-regulated by a combination of currently available therapeutics.

Global FT4 immunoassay standardization: an expert opinion review.

OBJECTIVES: Results can vary between different free thyroxine (FT4) assays; global standardization would improve comparability of results between laboratories, allowing development of common clinical decision limits in evidence-based guidelines. CONTENT: We summarize the path to standardization of FT4 assays, and challenges associated with FT4 testing in special populations, including the need for collaborative efforts toward establishing population-specific reference intervals. The International Federation of Clinical Chemistry and Laboratory Medicine Committee for Standardization of Thyroid Function Tests has undertaken FT4 immunoassay method comparison and recalibration studies and developed a reference measurement procedure that is currently being validated. Further studies are needed to establish common reference intervals/clinical decision limits. Standardization of FT4 assays will change test results substantially; therefore, a major education program will be required to ensure stakeholders are aware of the benefits of FT4 standardization, planned transition procedure, and potential clinical impact of the changes. Assay recalibration by manufacturers and approval process simplification by regulatory authorities will help minimize the clinical impact of standardization. SUMMARY: Significant progress has been made toward standardization of FT4 testing, but technical and logistical challenges remain. OUTLOOK: Collaborative efforts by manufacturers, laboratories, and clinicians are required to achieve successful global standardization of the FT4 assays.

Is point of care renal function testing reliable screening pre-IV contrast administration?

PURPOSE: Intravenous iodinated contrast is a commonly used diagnostic aid to improve image quality on computed tomography. There exists a small risk of post-contrast acute kidney injury in patients receiving IV contrast. One of the biggest risk factors for developing PC-AKI is the presence of pre-existing renal dysfunction, making it important to measure the renal function prior to contrast administration. Point of care (POC) devices offer a quick estimation of renal function, potentially improving workflows in radiology departments. METHOD: Two POC devices were evaluated, the Nova StatSensor and Abbott iSTAT. Patients undergoing routine radiological investigations had blood collected and analysed by a POC method and the laboratory method (Beckman AU5800). The two values were analysed and compared. Renal function was calculated using eGFR via the CKD-EPI result. eGFR values were stratified as high risk (eGFR < 30), moderate risk (eGFR 30-59) and low risk (eGFR ≥ 60). RESULTS: One hundred eighty-six patients were included in the study. One hundred one patients underwent the Abbott iSTAT analysis, 139 patients underwent Nova StatSensor analysis, and 53 had both. Statistical analysis revealed that the StatSensor R2 value was 0.77, and coefficient variation was 10.65%. iSTAT had a R2 value of 0.83 and coefficient variation of 7.36%. The POC devices did not miss any high-risk patients but underreported eGFR values in certain patients. CONCLUSION: POC devices are moderately accurate at detecting renal impairment in patients undergoing radiological investigations. They seem to be a good screening tool; however, any low eGFR values should be further examined.

Cord blood metabolic markers are strong mediators of the effect of maternal adiposity on fetal growth in pregnancies across the glucose tolerance spectrum: the PANDORA study.

AIMS/HYPOTHESIS: We aimed to assess associations between cord blood metabolic markers and fetal overgrowth, and whether cord markers mediated the impact of maternal adiposity on neonatal anthropometric outcomes among children born to Indigenous and Non-Indigenous Australian women with normal glucose tolerance (NGT), gestational diabetes mellitus (GDM) and pregestational type 2 diabetes mellitus. METHODS: From the Pregnancy and Neonatal Outcomes in Remote Australia (PANDORA) study, an observational cohort of 1135 mother-baby pairs, venous cord blood was available for 645 singleton babies (49% Indigenous Australian) of women with NGT (n = 129), GDM (n = 419) and type 2 diabetes (n = 97). Cord glucose, triacylglycerol, HDL-cholesterol, C-reactive protein (CRP) and C-peptide were measured. Multivariable logistic and linear regression were used to assess the associations between cord blood metabolic markers and the outcomes of birthweight z score, sum of skinfold thickness (SSF), being large for gestational age (LGA) and percentage of body fat. Pathway analysis assessed whether cord markers mediated the associations between maternal and neonatal adiposity. RESULTS: Elevated cord C-peptide was significantly associated with increasing birthweight z score (ß 0.57 [95% CI 0.42, 0.71]), SSF (ß 0.83 [95% CI 0.41, 1.25]), percentage of body fat (ß 1.20 [95% CI 0.69, 1.71]) and risk for LGA [OR 3.14 [95% CI 2.11, 4.68]), after adjusting for age, ethnicity and diabetes type. Cord triacylglycerol was negatively associated with birthweight z score for Indigenous Australian women only. No associations between cord glucose, HDL-cholesterol and CRP >0.3 mg/l (2.9 nmol/l) with neonatal outcomes were observed. C-peptide mediated 18% (95% CI 13, 36) of the association of maternal BMI with LGA and 11% (95% CI 8, 17) of the association with per cent neonatal fat. CONCLUSIONS/INTERPRETATION: Cord blood C-peptide is an important mediator of the association between maternal and infant adiposity, across the spectrum of maternal glucose tolerance.

Subclinical hypothyroidism during pregnancy: the Melbourne public hospitals consensus.

BACKGROUND: Interest in potential adverse outcomes associated with maternal subclinical hypothyroidism (normal free T4, elevated thyroid-stimulating hormone (TSH)) has increased significantly over recent years. In turn, the frequency of maternal thyroid function testing has risen, despite universal thyroid function screening not being recommended, leading to a marked increase in referrals to obstetric endocrinology clinics. In 2017 the American Thyroid Association revised their diagnostic and management guidelines. Although welcome, these new guidelines contain recommendations that may cause confusion in clinical practice. AIM: To ensure uniform practice in the diagnosis and management of subclinical hypothyroidism in pregnancy across all Melbourne public hospitals. METHODS: Endocrinology and obstetric representatives from all Melbourne public hospital networks reviewed the 2017 American Thyroid Association guidelines and other relevant literature to develop a consensus for diagnosing and treating subclinical hypothyroidism during pregnancy in Melbourne. The consensus guidelines were then referred to the Endocrine Society of Australia for comment and endorsement. RESULTS: Consensus was achieved and the guidelines were endorsed by the Council of the Endocrine Society of Australia. Trimester and assay-specific TSH reference intervals derived from healthy local populations should be used, where available. When unavailable, a TSH cut-off of 4 mU/L (replacing the previously recommended 2.5 mU/L) should be used to initiate treatment, irrespective of thyroid auto-antibody status. The recommended starting dose of levothyroxine is 50 µg daily, with a therapeutic TSH target of 0.1-2.5 mU/L. Levothyroxine should generally be ceased after delivery, with some exceptions. Hospitals will ensure smooth transfer of care back to the woman's general practitioner with clear documentation of pregnancy thyroid management and a recommended plan for follow-up. CONCLUSION: Fewer women will be classified as having subclinical hypothyroidism during pregnancy, which is likely to lead to reductions in emotional stress, hospital visits, repeated blood tests and financial costs. Uniform clinical practice will occur across Melbourne.

Pregnancy And Neonatal Diabetes Outcomes in Remote Australia: the PANDORA study-an observational birth cohort.

BACKGROUND: In Australia's Northern Territory, 33% of babies are born to Indigenous mothers, who experience high rates of hyperglycemia in pregnancy. We aimed to determine the extent to which pregnancy outcomes for Indigenous Australian women are explained by relative frequencies of diabetes type [type 2 diabetes (T2DM) and gestational diabetes (GDM)]. METHODS: This prospective birth cohort study examined participants recruited from a hyperglycemia in pregnancy register. Baseline data collected were antenatal and perinatal clinical information, cord blood and neonatal anthropometry. Of 1135 women (48% Indigenous), 900 had diabetes: 175 T2DM, 86 newly diagnosed diabetes in pregnancy (DIP) and 639 had GDM. A group of 235 women without hyperglycemia in pregnancy was also recruited. RESULTS: Diabetes type differed for Indigenous and non-Indigenous women (T2DM, 36 vs 5%; DIP, 15 vs 7%; GDM, 49 vs 88%, p < 0.001). Within each diabetes type, Indigenous women were younger and had higher smoking rates. Among women with GDM/DIP, Indigenous women demonstrated poorer birth outcomes than non-Indigenous women: large for gestational age, 19 vs 11%, p = 0·002; neonatal fat 11.3 vs 10.2%, p < 0.001. In the full cohort, on multivariate regression, T2DM and DIP were independently associated (and Indigenous ethnicity was not) with pregnancy outcomes. CONCLUSIONS: Higher rates of T2DM among Indigenous women predominantly contribute to absolute poorer pregnancy outcomes among Indigenous women with hyperglycemia. As with Indigenous and minority populations globally, prevention or delay of type 2 diabetes in younger women is vital to improve pregnancy outcomes and possibly to improve the long-term health of their offspring.

The stability and variability of serum and plasma fibroblast growth factor-23 levels in a haemodialysis cohort.

BACKGROUND: Serum fibroblast growth factor 23 (FGF-23) levels are markedly elevated in haemodialysis patients and have been linked to mortality outcomes. Small studies in health and chronic kidney disease, have demonstrated marked intra- and inter-individual variability in measured FGF-23 levels, and variable degradation in serum as compared to plasma samples. In end-stage kidney disease (ESKD), the intra- and inter-individual variability of FGF-23 levels, and the optimal collection methods remain poorly characterized. In this study we assessed the variability of FGF-23 levels in a cohort of stable haemodialysis patients. Secondly, in a subset of patients, we assessed the effects of different collection methods on measured FGF-23 levels. METHODS: To assess the variability of FGF-23, pre-dialysis blood samples were collected over 3 consecutive weeks from 75 haemodialysis patients. The effects of different specimen collection methods were examined in a subset of patients (n = 23), with pre-dialysis blood collected into different tubes: plain (serum), EDTA (plasma) and EDTA with the addition of a protease inhibitor (EDTA-PI). All analyses were performed in the main cohort and repeated in each subgroup. Variability over a 3-week period was assessed using repeated measures ANOVA and random effects linear regression models. Intra-class correlation coefficients were calculated to assess agreement, and coefficients of variation were calculated to assess intra- and inter-individual variability. RESULTS: Over the 3-week study period the mean FGF-23 levels were not significantly different in the serum (p = 0.26), EDTA (p = 0.62) and EDTA-PI (p = 0.55) groups. FGF-23 levels demonstrated marked intra- and inter-individual variability with a CV of 36 and 203.2%, respectively. In the subgroup analysis, the mean serum FGF-23 levels were significantly lower than the EDTA (p < 0.001) or EDTA-PI (p < 0.001) groups, however there was no difference in mean FGF-23 levels between EDTA and EDTA-PI (p = 0.54). CONCLUSIONS: The measured FGF-23 levels were significantly lower in serum as compared to plasma, and the addition of a protease inhibitor did not confer an additional benefit. Importantly in this cohort of ESKD patients, FGF-23 levels showed marked intra- and inter-individual variability. The routine measurement of FGF-23 in ESKD remains challenging, however this study suggests the plasma is the optimal collection method for FGF-23 analysis.

Reference intervals for neonatal thyroid function tests in the first 7 days of life.

BACKGROUND: Prompt intervention can prevent permanent adverse neurological effects caused by neonatal hypothyroidism. Thyroid function changes rapidly in the first few days of life but well-defined age-specific reference intervals (RIs) for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free tri-iodothyronine (FT3) are not available to aid interpretation. We developed hour-based RIs using data mining. METHODS: All TSH, FT4 and FT3 results with date and time of collection from neonates aged <7 days during 2005-2015 were extracted from the Monash Pathology database. Neonates with more than one episode of testing or with known primary hypothyroidism, identified by treating physicians or from medical records, were excluded from the analysis. The date and time of birth were obtained from the medical records. RESULTS: Of the 728 neonates qualifying for the study, 569 had time of birth available. All 569 had TSH, 415 had FT4 and 146 had FT3 results. For age ≤24 h, 25-48 h, 49-72 h, 73-96 h, 97-120 h, 121-144 h and 145-168 h of life, the TSH RIs (2.5th-97.5th) (mIU/L) were 4.1-40.2, 3.2-29.6, 2.6-17.3, 2.2-14.7, 1.8-14.2, 1.4-12.7 and 1.0-8.3, respectively; the FT4 RIs (mean ± 2 standard deviation [SD]) (pmol/L) were 15.3-43.6, 14.7-53.2, 16.5-45.5, 17.8-39.4, 15.3-32.1, 14.5-32.6 and 13.9-30.9, respectively; the FT3 RIs (mean±2 SD) (pmol/L) were 5.0-9.4, 4.1-9.1, 2.8-7.8, 2.9-7.8, 3.5-7.2, 3.4-8.0 and 3.8-7.9, respectively. CONCLUSIONS: TSH and FT4 were substantially high in the first 24 h after birth followed by a rapid decline over the subsequent 168 h. Use of hour-based RIs in newborns allows for more accurate identification of neonates who are at risk of hypothyroidism.

Higher maternal serum prolactin levels are associated with reduced glucose tolerance during pregnancy.

It is unknown if high prolactin levels during pregnancy contribute to the development of gestational diabetes. We hypothesized that higher prolactin levels are associated with reduced glucose tolerance, as determined by higher 2-h glucose level from an oral glucose tolerance test in pregnancy. The 75-g oral glucose tolerance test was carried out at 28 weeks of gestation in 69 participants. A multiple regression analysis was used to determine the relationship between serum prolactin and 2-h glucose levels. Multivariable regression analysis showed an independent and significant relationship between third trimester prolactin and 2-h glucose levels post oral glucose tolerance test. Higher prolactin levels were associated with higher glucose levels independent of age, body mass index, gravidity and parity. Higher prolactin levels associated with reduced glucose tolerance in the third trimester of pregnancy suggests the possible independent role of prolactin in the pathogenesis of gestational diabetes.

Cystatin C estimated glomerular filtration rate and all-cause and cardiovascular disease mortality risk in the general population: AusDiab study.

AIMS: Uncertainties about the role of cystatin C-based estimated glomerular filtration rate (eGFR) in the prediction of cardiovascular disease (CVD) beyond traditional CVD risk factors remain. We assessed contributions of eGFR to CVD and mortality in the general population. METHODS: Using 14 year follow-up data on 9353 adults without a reported history of CVD from the Australian Diabetes, Obesity and Lifestyle study, we assessed the contributions of eGFR (assessed by cystatin C (eGFRcysC ) and serum creatinine (eGFRcr ) and albuminuria (uACR) to total and CVD mortality. RESULTS: After adjusting for age, sex, CVD risk factors and uACR, compared with an eGFRcysC >90 mL/min per 1.73 m2 , eGFRcysC <60 mL/min per 1.73 m2 was associated with 56% and 73% increases in the risks for all-cause and CVD mortality, respectively. The respective changes for the c-statistic when eGFRcysC was added to a risk prediction model were 0.003 (95% confidence interval: 0.001 to 0.005) and 0.002 (95% confidence interval: -0.001 to 0.006). The net proportion of non-events assigned a lower-risk category significantly improved with the addition of eGFR (non-event net reclassification index eGFRcr : 1.0% and eGFRcysC : 1.5%) for all-cause mortality, but for CVD mortality, improvements were only significant when eGFR was combined with uACR. The net proportion of events assigned a higher-risk category was not significantly improved. CONCLUSION: In our community-based cohort, reduced eGFRcysC was associated with all-cause and CVD mortality. The addition of chronic kidney disease measures to risk prediction models improved overall risk stratification among those at low risk as opposed to those at high baseline risk of mortality.

Harmonisation of Osmolal Gap - Can We Use a Common Formula?

Osmolal gap is the difference between the measured osmolality and a calculated osmolality based on the major commonly measured osmotically active particles. The perceived gap indicates the presence of unmeasured osmotically active particles. The major use of osmolal gap today is to screen for the possible presence of exogenous toxic substances in patients in an emergency department or intensive care unit. There is a long history of osmolal gap calculations and it needs to be appreciated that the uncertainty of the osmolal gap will be determined by the sum of errors in the calculated osmolality, error in measured osmolality and variability in unmeasured analytes. Since 1958 there has been a constant trickle of papers proposing both simple and sophisticated formulae to calculate the 'ultimate' osmolal gap. A gap as close to zero as possible and with a low coefficient of variation across multiple clinical conditions and analytical platforms are also determinants of 'fitness for purpose' of any osmolal gap calculations. The Smithline-Gardner formula for calculated osmolality [2(Na) + Glu + Urea] is fit for purpose in both normal people and general hospital patients. It also performs well across different analytical platforms. This simple formula can be used for rapid mental calculation at the bedside and automated laboratory information system reporting whenever a measured osmolality is requested. In this era of harmonisation, we propose that this formula be adopted by all clinicians and laboratories.